How To Implement The Erosion Of The Morphology Of Image Processing?¶

Introduction

The erosion is one of the morphology. It is to make the gap between point and point. For example, if you want to break to another pixel. But you need a rule to process. The erosion is a good idea. Because it has a regular rule and you can control it. The means that you can set at times how much you want do it. Then, It is the erosion gradual until you don’t want to keep going.

Equipment

Operation System: Microsoft Windows 7 (64 bit)
Development Utility: Microsoft Visual Studio 2010

Usage

// The height of the image
for ( int iY = 1; iY < imageA->DibInfo->bmiHeader.biHeight - 1; iY++ )
{
    // The width of the image
    for ( int iX = 1; iX < imageA->DibInfo->bmiHeader.biWidth - 1; iX++ )
    {
        // The up of the index of the image
        lIDXA1 = ( iX * 3 ) + ( (iY-1) * imageA->DibInfo->bmiHeader.biWidth * 3 );
        // The down of the index of the image
        lIDXA2 = ( iX * 3 ) + ( (iY+1) * imageA->DibInfo->bmiHeader.biWidth * 3 );
        // The left of the index of the image
        lIDXA3 = ( (iX-1) * 3 ) + ( iY * imageA->DibInfo->bmiHeader.biWidth * 3 );
        // The right of the index of the image
        lIDXA4 = ( (iX+1) * 3 ) + ( iY * imageA->DibInfo->bmiHeader.biWidth * 3 );
        // If four directions have a white pixel and then the center pixel sets up white pixel.
        if ( imageA->DibArry[lIDXA1+0] == 255 || 
             imageA->DibArry[lIDXA2+0] == 255 ||
             imageA->DibArry[lIDXA3+0] == 255 ||
             imageA->DibArry[lIDXA4+0] == 255 )
        {
            // The index of the pixel. If your bit depth is not three, you should fix it.
            // This bit depth is 24 bits, so we use three bytes.
            lIDXB = ( iX * 3 ) + ( (iY) * imageB->DibInfo->bmiHeader.biWidth * 3 );
            // Set the center pixel to be white that means is erosion.
            imageB->DibArry[lIDXB+0] = 255;
            imageB->DibArry[lIDXB+1] = 255;
            imageB->DibArry[lIDXB+2] = 255;
        }
        // Otherwise, the center pixel is black.
        else
        {
            // The index of the pixel. If your bit depth is not three, you should fix it.
            // This bit depth is 24 bits, so we use three bytes.
            lIDXB = ( iX * 3 ) + ( (iY) * imageB->DibInfo->bmiHeader.biWidth * 3 );
            // Set the center pixel to be black.
            imageB->DibArry[lIDXB+0] = 0;
            imageB->DibArry[lIDXB+1] = 0;
            imageB->DibArry[lIDXB+2] = 0;
        }
    } // The closing "The width of the image".
} // The closing "The height of the image".

You can download source code and binary code as below:
https://drive.google.com/file/d/0BzHb_OyLyVZldjVRZEpZUmlvMHc/view?usp=sharing

Exception

1. There is a notice, if your bit depth of bitmap file are not 24 bits, you should change your bitmap files to adapt this program, or you could rewrite this source code to fit your bitmap format.

2. You have to install Microsoft SDK v7.1, because I include windowscodes.lib.
   #pragma comment(lib, "windowscodecs.lib")

Reference

[1] Gary Bradski and Adrian Kaehler, “Learning OpenCV: Computer Vision with the OpenCV Library,” O’REILLY, September 2008, ISBN:978-0-596-51613-0

Acknowledge

Thank you (Microsoft Visual Studio 2010) very much for this great development utility.